Sudan's parliament has branded South Sudan's government an "enemy" and called for a swift recapture of a disputed oil-producing region, as rising border tensions pushed the old civil war foes closer to another full-blown conflict.

South Sudan, which seceded from Sudan last July, seized the contested Heglig oilfield last Tuesday, prompting its northern neighbour to vow to recapture the area by "all means".

"We declare that we will confront the SPLM until we end its rule of the South, and will work to gather our resources to realise this aim," he said. "We are in a battle that does not finish with the recovery of Heglig, but with an end to the danger that comes from South Sudan."

The assembly went on to adopt a resolution describing the SPLM government as "an enemy", but it did not spell out the full implications of the decision.

South Sudanese Information Minister Barnaba Marial Benjamin called the decision "ludicrous". "How can they call us an enemy?" he said.

South Sudan insists Heglig is rightfully part of the South and says it will not withdraw its troops unless the United Nations deploys a neutral force to monitor a ceasefire.

It accused Khartoum on Sunday of reducing the oil facility "to rubble" in an air strike, an accusation denied by Sudan.

"If any damage has occurred in Heglig it may have been on the part of the army of South Sudan," Sudanese Information Minister Abdallah Ali Masar said.

UN camp targeted

Meanwhile, the United Nations Mission in South Sudan (UNMISS) has confirmed that a UN peacekeepers' camp was among targets bombed by Sudanese warplanes.

Kouider Zerrouk, spokesman for the UNMISS, said on Monday that there had been no casualties in Sunday's attack.

But a South Sudanese minister said that seven civilians had been killed and 14 others wounded in an attack on Mayom, while the region of Bentiu was also bombed.

Gideon Gatpan, the minister, said that two bombs had fallen in the UN camp, destroying a generator and a radio.